If you had to pin it on a single actor, Google. Ads have corrupted the original vision of the web. When you offer a path for other actors to monetize the web, they will, and Google did that more than anybody.
Google has made so many "death of the web" moves over the past few years that it's hard for them not to be implicated in the current situation. If they've shat in their own pants, well that's too bad.